HELP my YJ won't shift into gear while on, but will when turned off. - JeepForum.com
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Unread 07-01-2012, 08:04 PM   #1
blevinsr
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HELP my YJ won't shift into gear while on, but will when turned off.

YJ AX15 tranny worked before but it would grind while shifting into 2nd and 3rd. Dropped the tranny then had a shop rebuild it. The shop has excellent references and my buddies that use them have never gotten a tranny back that wasn't right. The shop did the rebuild as well as the put in a new slave cylinder. The shop said that the synchros were bad, and that at some point water had gotten into it.

Put the tranny back in and it will shift into all gears while off, with no problems. Start it up and it will not shift into any gear. Started it while in gear and it will move forward, or backward when in reverse.

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Unread 07-01-2012, 08:10 PM   #2
UltimatE
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The clutch isn't releasing properly. Either a mechanical failure in the clutch system (Pressure plate, flywheel, clutch disk, etc) or something wrong with the hydraulics.
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Unread 07-01-2012, 09:25 PM   #3
blevinsr
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Yep

You're probably right. Clutch pedal has excellent pressure throughout entire length of throw. The synchros were just replaced. We bled the air out of the new slave. We're thinking the clutch as well but don't want to have to buy a clutch and drop the tranny AGAIN until we are sure.
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Unread 07-01-2012, 09:33 PM   #4
bigbossd1030
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pump the pedal a few times while it is on, then try and shift. Id pump about 10 to 15 times, if it works, you are loosing some pressure. its more than likely the mc if this happens.
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Unread 07-01-2012, 10:11 PM   #5
ezk83
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Thats what mine was doing when i shattered my clutch plate. So if your not losing preasure drop the trans and check the clutch.
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Unread 07-01-2012, 10:20 PM   #6
Bl4cK_kNiF3
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Did you swap to the external slave setup or keep the internal? the new style external slave cylinder is nearly impossible to bleed and wont let the clutch fully disengage if you have air in it. Thats what happened to mine. it is supposed to be replaced as a sealed, prebled unit.

if you have the internal setup, i would try bleeding it again after checking for leaks. The master cylinder commonly leaks and is seen from inside the jeep along the firewall where it connects to the clutch pedal.

Did you put a new clutch kit on while the trans was out? I always reccomend putting a new clutch kit and flywheel on while its already out of the vehicle just to start fresh.
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Unread 07-01-2012, 10:27 PM   #7
blevinsr
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We kept the internal slave. Have bled it numerous times and checked for leaks. The clutch was replaced 6 months so we left it alone this time. One possibility is that the new clutch was damaged by driving around for a couple of months with the bad synchros.
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Unread 07-02-2012, 02:55 AM   #8
Mark05059
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bad syncros wont damage your clutch
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Unread 07-02-2012, 03:51 AM   #9
90DesertTanYJ
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Something in the clutch is not engaging. Classic signs. Maybe the clutch fork is in the wrong position. Your gonna hafta pull it apart and see.
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Unread 07-03-2012, 12:11 AM   #10
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Update

Update: We took the tranny back out and found the pilot shaft (or input shaft) bearing had failed. The outer race is stuck in flywheel. Does anyone know if the throw out bearing/slave cylinder requires the pin/dowel? We bought a replacement clutch/clutch plate/throw out bearing and it came with a new pin, however, the existing throw out bearing (with was replaced last week) did not have the pin. If required could it have caused the bearing to fail?
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Unread 12-03-2013, 01:46 PM   #11
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i have a 90 yj with a 4.2l and a 5 speed ax15 ,i was driveing from work fine stoped at a stop sign and when i pushed the clutch in and went to shift into 1rst gear it wouldnt go nor any other gear.with engine off it wouldnt go into a gear with or with out the clutch . the mc is full and no leaks and slave cylinder has presure in the pedal but yet it wont shift .had to tow home at least it died in nutruel. what could cause this?
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